Page 274 - HVAC Pump Handbook

Rishel_09.qxd 20/4/06 6:34 PM Page 271

Configuring an HVAC Water System

Configuring an HVAC Water System 271

T
From pumps
To
building
To pump ∆P
speed control

To pumps
Building
pump
Locate differential pressure
transmitter for system
pumps if this is a critical
building or at the point
of highest pressure loss
in system.
Figure 9.13 Heat exchanger for high risk building. (From Patterson Pump
Company HVAC Pumps and Systems Manual, 2004.)

One of the concerns for the control valve of Fig. 9.13 is the great loss
that may be incurred in it at light loads on the building. Through
adaptive control, the set point for the differential pressure transmitter
can be reset on light loads through a valve position indicator/transmitter
on the control valve as per Fig. 9.14. The differential pressure across

Valve position indicator-
transmitter
To pump speed
control T

From pumps To
building
To pump ∆P
speed control

To pumps
Building
Heat exchanger
pump
Set point is adjusted by
valve position to hold
valve to 80 to 85 % open
Figure 9.14 Valve position control on heat exchanger.

Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2006 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.